fix: Trim the trailing slash of baesUrl

[Himenon]

Summary

Invalid code

let baseUrl = "https://api.example.com/"

....
baseUrl + "/a/b/c";
# => https://api.example.com//a/b/c

Code that works reliably

let baseUrl = "https://api.example.com/"

....
baseUrl.replace(/\/$/, "") + "/a/b/c";
# => https://api.example.com/a/b/c

Test Plan